Zero looseness fastener for linkage assembly

ABSTRACT

A fastener is used to connect a first link to a second link in a vehicle seat assembly. The fastener has a head portion and a body portion extending outwardly from the head portion and defining an external diameter. The body portion is generally cylindrical and has a central bore with an internal diameter that is less than the external diameter. The method for connecting the first link to the second link with the fastener includes the steps of inserting the central body portion through aligned apertures in the links to form a subassembly and holding the subassembly fixed while a tooling member applies a linear load to the distal end of the body portion. The tooling member is inserted into the central bore and deforms the body portion for engagement with the first and second links to allow relative rotational movement between the links while eliminating relative linear movement therebetween.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a divisional application of U.S. patentapplication Ser. No. 09/130,428 filed Aug. 6, 1998.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

[0002] Not Applicable

REFERENCE TO MICROFICHE APPENDIX

[0003] Not Applicable

FIELD OF THE INVENTION

[0004] This application relates to a fastener used for connecting afirst link member to a second link member and more particularly to afastener having a body portion that is deformed to engage the members inorder to eliminate free play while still allowing relative rotationalmovement.

BACKGROUND OF THE INVENTION

[0005] Linkage assemblies are often used in seat assemblies to providevarious functions including seat adjustment capability. Linkageassemblies typically include two or more link members, which are joinedto each other by using various methods. The link members typicallyreceive input from an adjuster control member which causes the links torotate relative to one another to achieve a desired position. In knownlinks, as the links rotate there has typically been free play or linearmovement between the links. This free play is detrimental to thestability of the adjuster.

[0006] Various methods have been used to eliminate the free play betweenlink members. Often bushings or bushing materials are used in the linkassembly to take up the free play yet permit the links to rotaterelative to one another. This is expensive and requires additionalassembly time and materials.

[0007] Thus, it is desirable to eliminate the use of bushings andbushing type materials from linkage assemblies by providing a linkageassembly that uses a fastener which allows relative rotational movementbetween link members but eliminates free play between the members. Byeliminating the use of bushings, the cost of the linkage assembly isreduced and assembly time is decreased.

SUMMARY OF THE INVENTION

[0008] In a disclosed embodiment, a fastener used to connect a firstmember to a second member includes a head portion and a body portion.Preferably, the first and second members are links in a seat adjusterassembly. The body portion extends outwardly from the head portion anddefines an external diameter. The body portion is generally cylindricaland has a central bore with an internal diameter that is less than theexternal diameter. The body portion is deformable for engagement withthe first and second members to allow relative rotational movementbetween the members while eliminating relative linear movementtherebetween.

[0009] The preferred inventive method for connecting a first member to asecond member includes providing a fastener having a head portion and acylindrical body portion extending therefrom and terminating at a distalend, a first member having a first aperture, and a second member havinga second aperture. The first aperture is aligned with the secondaperture, the body portion of the fastener is inserted into the firstand second apertures, and the body portion is deformed into engagementwith the first and second members to allow relative rotational movementbetween the members while eliminating relative linear movement betweenthe members.

[0010] Deforming the body portion of the fastener eliminates undesirablefree play between the two members while still allowing the members torotate with respect to each other. The fastener eliminates the use ofexpensive bushings and is easily installed, easily maintained, and isinexpensive. These and other features can be understood from thefollowing specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a perspective view of a seat track assembly with alinkage subassembly using the subject fastener;

[0012]FIG. 2 is a top view of a linkage assembly with the subjectfastener; and

[0013]FIG. 3 is a cross sectional view of the linkage assembly of FIG. 2shown with a tooling member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0014] A vehicle seat mounting assembly is shown generally at 10 inFIG. 1. The seat mounting assembly 10 includes a lower track 12 that ismounted to a vehicle floor 14 and an upper track 16 that slides withrespect to the lower track 12 for seat adjustment in a forward orrearward position. The seat mounting assembly 10 also includesadjustment capability for adjusting the seat vertically. The verticaladjuster assembly is shown generally at 18 and includes a linkageassembly 20 which allows the seat to be raised or lowered to accommodateoccupants of varying heights.

[0015] The linkage assembly 20 is shown in more detail in FIG. 2. Afirst link member 22 is connected to a second link member 24 with afastener 26. A typical linkage assembly 20 includes at least two linkmembers 22, 24, however, a greater number of link members can be usedwith the subject fastener. Only two link members 22, 24 are shown forsimplicity. The fastener 26 used to connect the links 22, 24 allows thelinks to rotate relative to one another.

[0016] A cross-sectional view of the inventive fastener 26 is shown inFIG. 3. The fastener is preferably made from a low carbon steel such asSAE 1010, however, aluminum, zinc or other materials well known in theart could be used. The fastener 26 includes a head portion 28 and a bodyportion 30 extending outwardly from the head portion 28 and defining anexternal diameter D1. The head portion 28 is preferably circular,however, other shaped heads could be used. The body portion 30 iscylindrical and has a central bore 32 with an internal diameter D2 thatis less than the external diameter D1. The body portion 30 is preferablyperpendicular to the head portion 28. The body portion 30 is deformablefor engagement with the first and second link members 22, 24 to allowrelative rotational movement between the members 22, 24 whileeliminating undesirable relative linear movement or free-play betweenthe members 22, 24.

[0017] The body portion terminates at a distal end 34, which receives alongitudinal load for deforming the body portion 30. The longitudinalload is preferably applied linearly to the distal end 34 of the bodyportion 30. The longitudinal load causes the internal and externaldiameters D1, D2 to increase resulting in the body portion 30 expandingoutwardly to engage the first and second members 22, 24 to hold thefastener 26 firmly in place. The body portion 30 is preferablyplastically deformed such that the shape and/or size of the body portion30 is permanently changed due to the sustained application of the loadbeyond the elastic limit of the material.

[0018] The fastener 26 is shown in FIG. 3 before and after deformation.The post deformation fastener 26 is shown with the cross-hatched lines.As the load is applied to the distal end 34 of the body portion 30, thedistal end 34 bends transversely to the longitudinal load and forms alip for engaging one of the members. The lip 36 locks the fastener 26 toone of the members to prevent relative rotational movement between theone member and the fastener 26 while allowing the other member to movefreely. Thus, the fastener 26 holds the link members 22, 24 together andallows relative rotational movement between the members 22, 24, but isfixed to one of the two link members to prevent rotation between thatlink member and the fastener 26. This will be discussed in greaterdetail below.

[0019] The first link 22 has a first external surface 38, a firstinternal surface 40, and a first aperture 42 extending between theexternal and internal surfaces 38, 40. The second link 24 has a secondexternal surface 44, a second internal surface 46, and a second aperture48 extending between the external and internal surfaces 44, 46. The bodyportion 30 is first inserted through the first and second apertures 42,48 and then is plastically deformed to engage the first and second links22, 24 to hold the fastener 26 in place.

[0020] The first link 22 has a first thickness T1, the second link 24has a second thickness T2, and the body portion 30 has a length L thatis greater than the sum of the first and second thicknesses T1, T2 suchthat when the internal face 40 of the first link 22 is placed againstthe internal face 46 of the second link 24 and the body portion 30 isinserted through the first and second links 22, 24, a segment 50 of thebody portion 30 extends beyond the links 22, 24 as assembled. The linearload that is applied to the distal end 34 of the body portion 30 causesthe segment 50 of the body portion 30 to bend transversely with respectto the linear load. This forms the lip 36 for engaging the externalsurface 44 of the second link 24. The second link 24 is locked to thefastener 26 via the lip 36 to prevent relative rotational movementbetween the second link 24 and the fastener 26 while allowing the firstlink 22 to move freely.

[0021] The method for connecting the first link 22 to the second link 24includes the steps of aligning the first aperture 42 with the secondaperture 48, inserting the body portion 30 of the fastener 26 into thefirst and second apertures 42, 48, and deforming the body portion 30into engagement with the first and second links 22, 24 to allow relativerotational movement between the links 22, 24 while eliminating freeplay. The step of deforming the body portion 30 includes applying alongitudinal load to the distal end 34 of the body portion 30 to causethe deformation.

[0022] Additional steps include holding the internal face 40 of thefirst link 22 against the internal face 46 of the second link 24 andinserting the body portion 30 of the fastener 26 through the first andsecond apertures 42, 48 such that the head portion 28 engages theexternal face 38 of the first link while the segment 50 of the bodyportion 30 extends beyond the external face 44 of the second link 24.The longitudinal load is applied to the distal end 34 of the bodyportion 30 and the segment 50 of the body portion 30 bends transverselywith respect to the longitudinal load to form the lip 36 that partiallyengages the external face 44 of the second link 24. As the lip 36 isbent under the load, the second link 24 is locked to the fastener 26 sothat there is no relative rotational movement between the second link 24and the fastener 26 while allowing the first link 22 to move freely.

[0023] A tooling member 52 is used to provide the load that deforms thebody portion 30 of the fastener 26. First, a subassembly comprised ofthe first link 22, the second link 24, and the fastener is created. Thesubassembly is held fixed and the tooling member 52 is loved along alinear path toward the subassembly to engage the body portion 30 fordeformation.

[0024] The tooling member 52 has an extension 54 with a diameter that isless than the internal bore diameter D2 and which has a curved exteriorsurface 56 surrounding the extension 54. The tooling member 52 appliesthe longitudinal load as the extension 54 is inserted into the bore 32such that the curved exterior surface 56 engages the distal end 34 ofthe body portion 30, causing the body portion 30 to swell or expandoutwardly. The distal end 34 of the body portion 30 is deformed bypressing the extension 54 further into the bore 32 causing the distalend 34 to bend outwardly along the curved surface 56 of the toolingmember 52 to form the lip 36. Thus, once the body portion 30 hasexpanded with the apertures 42, 48 to its maximum limit, the segment 50of the material is bent transversely to the load applied by the toolingmember 52 to form the lip 36.

[0025] The use of the subject fastener in a linkage assembly 20 providesrelative rotational movement between link members 22, 24 whileeliminating undesirable free play or relative linear movement betweenthe members 22, 24. This eliminates the need for expensive bushings orbushing type materials, thus reducing cost and assembly time.

[0026] Preferred embodiments of this invention have been disclosed,however, a worker of ordinary skill in the art would recognize thatcertain modifications would come within the scope of this invention. Forthat reason the following claims should be studied to determine the truescope and content of this invention.

What is claimed is:
 1. A vehicle seat mounting assembly comprising, incombination: at least one movable seat track; a linkage assemblyincluding: a first link having a first external surface, a firstinternal surface, and a first aperture extending between the firstexternal surface and the first internal surface; a second link having asecond external surface, a second internal surface, and a secondaperture extending between the second external surface and the secondinternal surface; a fastener having a head portion and a cylindricalbody portion extending therefrom and terminating at a distal endopposite said head portion; and wherein said body portion extendsthrough said first and second apertures and is plastically deformed sothat the fastener secures the first and second members to allow relativerotational movement between the first and second members whilepreventing relative linear motion therebetween; and wherein said linkageassembly is operably connected to said seat track to move said seattrack.
 2. A vehicle seat mounting assembly as recited in claim 1,wherein said first link has a first thickness, said second link has asecond thickness, and said body portion has a length that is greaterthan the sum of the first thickness and the second thickness such thatwhen said internal face of said first link is placed against saidinternal face of said second link and said body portion is insertedthrough said first and second links, a segment of said body portionextends beyond said links.
 3. A vehicle seat mounting assembly asrecited in claim 2, wherein the distal end of the body portion forms alip engaging an external surface of the second link.
 4. A vehicle seatmounting assembly as recited in claim 3, wherein said second link islocked to said fastener via said lip to prevent relative rotationalmovement between said second link and said fastener while allowing saidfirst link to move freely relative to said first link and said fastener.5. A vehicle seat mounting assembly as recited in claim 1, wherein: thefirst link has a first thickness between a first external surfaceengaged by the head portion and a first internal surface engaged by thesecond link, and a first aperture extending between the first externalsurface and the first internal surface; the second link has a secondthickness between a second external surface engaged by the body portionand a second internal surface engaged by the first internal surface, anda second aperture extending between the second external surface and thesecond internal surface; and the body portion has a length which isgreater than the sum of the first thickness and the second thicknesssuch that the first internal surface of the first link is positionedagainst the second internal surface of the second link, the body portionextends through the first and second apertures of the first and secondlinks, and a segment of the body portion extends beyond the first andsecond members.
 6. A vehicle seat mounting assembly as recited in claim1, wherein said body portion has a central bore with an internaldiameter.
 7. A vehicle seat mounting assembly as recited in claim 6,wherein: said first link has a first thickness; said second link has asecond thickness; and the central bore has a length which is greaterthan the first thickness and less than the sum of the first thicknessand the second thickness.
 8. A vehicle seat mounting assembly as recitedin claim 6, wherein said central bore extends for a length less than thetotal length of the body portion.
 9. A vehicle seat mounting assembly asrecited in claim 6, wherein said central bore is open at the end of thebody portion opposite the head portion and is closed toward the bodyportion.
 10. A vehicle seat mounting assembly as recited in claim 1,wherein said linkage assembly is operably connected to said seat trackto vertically move said seat track.
 11. A vehicle seat mounting assemblyas recited in claim 1, wherein said body portion comprises plasticallydeformable material for forming a lip at the distal end and engaging onethe first and second links.
 12. A vehicle seat mounting assembly asrecited in claim 1, wherein the cylindrical body portion has an externaldiameter and said head portion is enlarged such that the head portionextends radially outward beyond the external diameter of the bodyportion
 13. A vehicle seat mounting assembly comprising, in combination:at least one movable seat track; a linkage assembly including: a firstlink having a first external surface, a first internal surface, and afirst aperture extending between the first external surface and thefirst internal surface; a second link having a second external surface,a second internal surface, and a second aperture extending between thesecond external surface and the second internal surface; a fastenerhaving a head portion and a body portion extending outwardly from saidhead portion and defining an external diameter, said body portion beinggenerally cylindrical and having a central bore with an internaldiameter, and the central bore has a length which is greater than thefirst thickness and less than the first thickness and the secondthickness combined; and wherein said body portion extends through saidfirst and second apertures and is plastically deformed so that thefastener secures the first and second members to allow relativerotational movement between the first and second members whilepreventing relative linear motion therebetween; and wherein said linkageassembly is operably connected to said seat track to move said seattrack.
 14. A vehicle seat mounting assembly as recited in claim 13,wherein the body portion of the fastener has a length that is greaterthan the sum of the first thickness and the second thickness such thatwith the first internal surface of the first link positioned against thesecond internal surface of the second link and the body portionextending through the first and second apertures of the first and secondlinks with the head portion engaging the first external surface, asegment of the body portion extends beyond the first and second links.15. A vehicle seat mounting assembly as recited in claim 13, whereinsaid body portion terminates at a distal end opposite said head portionand said distal end is plastically deformed by a longitudinal load in adirection from the distal end toward the head portion.
 16. A vehicleseat mounting assembly as recited in claim 15, wherein said distal endis plastically deformed to form a lip for engaging one of the first andsecond links.
 17. A vehicle seat mounting assembly as recited in claim16, wherein said lip locks the fastener to one of the first and secondlinks via said lip to prevent relative rotational movement between theone link and the fastener while allowing the other link to rotate aroundthe fastener.
 18. A vehicle seat mounting assembly as recited in claim13, wherein said central bore extends from an end of the body portionopposite the head portion for a length less than the total length of thebody portion.
 19. A vehicle seat mounting assembly as recited in claim13, wherein said linkage assembly is operably connected to said seattrack to vertically move said seat track.
 20. A vehicle seat mountingassembly as recited in claim 13, wherein the cylindrical body portionhas an external diameter and said head portion is enlarged such that thehead portion extends radially outward beyond the external diameter ofthe body portion.